This application claims priority of DE 198 57 387.1-16, filed Dec. 12, 1998, the disclosure of which is expressly incorporated by reference herein.
The present invention relates to an arrangement for coupling the vertical position of a headrest assigned to a backrest of a motor vehicle seat with the withdrawal and retraction movement of a seat belt system with a belt retractor. More particularly, the present invention relates to an arrangement in which when the seat belt is put on by a vehicle occupant sitting in the vehicle seat, into a movement of the headrest from a lower inoperative position into an upwardly displaced operative position and, when the seat belt is taken off, into an opposite movement of the headrest back into the inoperative position, and the arrangement comprising a locking unit by means of which the headrest can be fixed in its operative position.
An arrangement is described in DE 38 07 928 C2, in which, when an occupant sitting in the motor vehicle seat puts on a seat belt, the withdrawal movement of a belt strap is transformed into a movement of the headrest from an inoperative position into an operative position displaced in the upward direction. Correspondingly, when the seat belt is taken off, the retraction movement of the belt strap is transformed into an opposite movement of the headrest back into the inoperative position. The arrangement is suitable particularly for vehicle seats in the rear of an occupant compartment because, when the seat in unoccupied, the headrest is in the bottom operating position and therefore allows the driver of the motor vehicle an unimpaired view to the rear over the unoccupied seats.
In the backrest of the known vehicle seat, a gearing is provided which transforms the rotating movement of a retractor during the withdrawal movement and the retraction movement of the belt strap into an adjusting movement of the headrest approximately in the longitudinal direction of the backrest. For this purpose, the rotating movement of the retractor is transmitted by way of an adjusting shaft to a driving pinion which, in the lower operating position of the headrest, engages with a serrated strip arranged on a guide rod of the headrest.
In addition, the adjusting shaft actuates a locking member by way of which the headrest can be locked in the operative position. For this purpose, the locking member comprises a locking bolt which interacts with a locking recess in the guide rod of the headrest. As soon as, in the course of the withdrawal movement of the seat belt, while the belt is approximately half pulled out, the headrest has reached its upper operative position, the locking bolt slides into the locking recess in the guide rod and slightly lifts the guide rod so that the serrated strip disengages from the driving pinion. As a result, the headrest is locked at the height pinion. As a result, the headrest is locked at the height predetermined by the locking recess. When the seat belt is taken off, the locking bolt interacts with the locking recess such that the serrated strip engages again with the driving pinion and the headrest can therefore be changed back into the inoperative position.
Another known arrangement is described in DE 30 20 558 C2, in which, when the seat belt is put on and taken off, the vehicle occupant sitting in the motor vehicle seat transforms the withdrawal or retraction movement of the belt strap into a swivelling movement of the headrest from a lower deposited position into an upper operative position. For this purpose, for example, by way of a buckle latch of the seat belt introduced at the end of buckling operation into a belt buckle, a circuit is closed, and the headrest is swivelled upward by an electric gearing connected to the circuit. In the operative position, the headrest is secured in a defined position a brake assigned to the geared motor. When the buckle latch is unlatched, a reversed control of the geared motor and a return of the headrest into the deposited position takes place.